A pet litter box in its basic form has a cat pan made from material such as plastic or metal, and filled with waste absorbing material or “litter”. Pet owners have to clean it with a scoop and periodically replace the used litter. This can be very unpleasant and inconvenient.
A set of disposable liners for a cat pan is shown in U.S. Pat. No. 5,121,712, to inventor Schulein, issued Jun. 16 1992. It provides a stack of thin, flexible sheets with a plurality of sifting apertures on each sheet which are vertically aligned with every other sheet. A shortcoming of these types of liners are that urine may pass through the aligned apertures, accumulating at the bottom layer for weeks and creating odor. Also, the wet clumping litter sticks together in some of the aligned holes, making the liners difficult to separate, so most cats (non declawed cats) may pull up the stick together liners with their claws, causing the free flowing litter to sink to the bottom through the open aligned holes and resulting not enough litter on the top layer, sometimes the whole set cannot be used anymore. Furthermore, the liners are typically secured by a rubber band to the rim of a pan, such as for example, Alpha Pet™ kitty cat premium cat pan liners and Van Ness™ sifting cat pan liners. However, it is cumbersome to apply the rubber band, and then to repeatedly remove and reapply it each time the litter is sifted. In addition, cats may claw to shreds the liners that are hanging against the walls of the pan.
U.S. Pat. No. 3,809,013, to inventors Doonan N, Hollis S, Rigney J, issued May 7, 1974. The disclosure includes a set of liners provided with flaps that close the aligned sifting apertures as long as they are in the litter box with litter on it, and open when lifted from the box. The short coming is, the aligned closable flaps tend to stick together, forming bumps on the flat surface of the liner, so non declawed cats may easily hook these bumps with their claws and pull out all the liners. The Doonan disclosure also provides a cover that can be placed over the tray and to hide the pan within the cover. However, cats may claw to pull out the liners that hanging on the rim and against the inner surface of the pan. Another type of cover of the disclosure is provided to place into the receptacle, unfortunately, the cover is loosely put on top of the uneven litter. Also, the liners are quite bulky along the exterior wall of the pan, cats may claw to shreds the overhanging liners. In addition, it still needs a rubber band to fix the liners on the rim of the pan.
U.S. Pat. No. 5,983,832, to inventor Eun Sook Seo, issued Nov. 16, 1999, is to provide a cover with open bottom that protects the liners on the rim as well as against the inner surfaces of the pan. However, the liners are quite bulky along the exterior wall of the pan, so cats may claw to shreds the overhanging liners. In addition, these covers do not include a high wall shields, so the pan has to be high enough to prevent a cat from urinating and defecating outside the pan. The higher pans require larger liners, which are difficult for pet owners to handle and the cost is higher. Furthermore, these covers do not eliminate the need for a rubber band.
U.S. Pat. No. 4,615,300, to inventor John P. McDonough, issued Oct. 7, 1986, provided an imperforate flap attached beneath the bottom of each screening layers by a flexible edge connector, the flap being large enough to cover all of the openings. The animal excrement may be screened from the litter by pulling upward on the uppermost layer, allowing the litter to pass through the openings as the flap drops down. The shortcomings are that they are too complicated and the cost is higher. In addition, the soiled imperforate sheets are unpleasant to handle, because they have to be folded with hands to fit into the opening of a normal sized trash can.
United States patent 20120325159 to inventor Ronald Penner, issued Dec. 27, 2012 is provided a set of rigid reusable sifting pans. While not vulnerable to claw to shreds, the holes in the pans tend to become easily clogged by wet clumped litter and are very difficult to clean.
The above problems and other problems are addressed by this disclosure as summarized below.